The present invention relates to a propellant support apparatus, which helps a self-propelled colonoscope to move forward in a patient's colon. More particularly, it relates to a propellant support apparatus, which is used to propel a self-propelled colonoscope, insertable into the colon, in a self-propelling manner, by driving a plurality of endless belts, mounted along the outside of the flexible section of the insertion tube of the colonoscope.
A colonoscope which does not cause pain to a patient and is capable of smooth insertion into the colon during colono-endoscopic examination has been sought. As such an endoscope, a colonoscope insertable, in a self-propelling manner, along the inside surface of the colon has been provided.
The inventor of the present invention disclosed in Japanese Patent Laid-open No.8-38416 an endoscope capable of self-propelling in the colon of a patient, by driving a plurality of endless belts, mounted along the outside of the flexible section of an insertion tube thereof.
The disclosed colonoscope is provided with a plurality of endless belts along the substantially entire length of the outside surface of the flexible section of the insertion tube thereof.
Each of the endless belts is preferably made of a flexible, strong and optimally adhesive material to be self-propelled along the wall of the colon. As a suitable material, a carbon fiber, synthetic fiber, metallic fiber or rubber may be preferable. The surface of each of the endless belts, made of the material mentioned above, may be preferably coated with an adequately adhesive material to get more adhesion.
And, the adequate adhesion of the endless belts is available to prevent a little loosened endless belts from running idle.
The endless belt are driven by a driving means mounted at the driving section of the colonoscope, and the outside circles of the endless belts contact the wall of the colon, so that frictional force between the colon wall and said endless belts will allow the distal end of the colonoscope to move spontaneously forward through the colon. The inside circle of each of the endless belts passes through one of guide pipes, provided in the flexible section of the insertion tube, leads to the distal end of the flexible section of the insertion tube, and comes out to the outside surface of the insertion tube again, whereby the endless belts rotate endlessly. Consequently, contacting the colon wall, the colonoscope can move spontaneously forward in the colon without excessive extending or bending the colon, which may be caused by pushing a conventional endoscope into the colon. That is, the self-propelled colonoscope is smoothly insertable into the colon, keeping the position and shape of the colon in physiological conditions, so that little pain may be caused to the patient.
The insertion tube of the colonoscope comprises a distal section having a length of about 1 to 2 cm, a bending section having a length of about 10 cm, and a flexible section extending from the flexible section to an operating section thereof. The distal section and the bending section are not provided with the endless belts so that the bending section can bend upwardly and downwardly, right and left, or obliquely on insertion.
Upon insertion of a colonoscope into to the colon, the insertion tube thereof is inserted through the anus, which is a narrow canal and about 5 cm in length, then into the rectum, and further into the sigmoid colon. The whole length of the rectum is about 20 to 21 cm. Since the end portion of the rectum, 14 to 15 cm long, is ampullar, at this end portion, the insertion tube and the endless belts hardly contact the colon wall.
On the other hand, a colonoscope can be manually inserted into the colon, without causing pain to a patient, up to a 25 cm site from the outlet of the anus, which is the same as the total length of the anus and the rectum. Accordingly, the self-propelled colonoscope can be manually inserted into the colon for about 25 cm from the outlet of the anus, and then can be self-propelled by driving the endless belts. However, when the endless belts are started to drive, a portion where the endless belts contact is only 5 to 7 cm, which is the length from the outlet of the anus to around the outlet of rectum.
When the endless belts of a self-propelled colonoscope are started to drive, because of no endless belts provided at a portion of 12 cm from the distal end of the colonoscope, a length of only about 13 cm is allowed for insertion of the endless belts into the anus and the rectum. Thus the insertion tube may not be insertable into the colon smoothly, or the excessive friction between the insertion tube and the walls of the anus and the rectum causes pain to the patient or bleeding.